Premium
The LD loop as an important structural element required for transmission of the allosteric signal in the HtrA (DegP) protease from Escherichia coli
Author(s) -
Figaj Donata,
Gieldon Artur,
Bartczak Marlena,
Koper Tomasz,
Zarzecka Urszula,
Lesner Adam,
Lipinska Barbara,
SkorkoGlonek Joanna
Publication year - 2016
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13822
Subject(s) - allosteric regulation , proteases , protease , escherichia coli , serine protease , serine , biochemistry , biology , protein structure , hydrolase , enzyme , chemistry , biophysics , microbiology and biotechnology , gene
High‐temperature requirement A (HtrA; DegP) from Escherichia coli , an important element of the extracytoplasmic protein quality‐control system, is a member of the evolutionarily conserved family of serine proteases. The characteristic feature of this protein is its allosteric mode of activation. The regulatory loops, L3, L2, L1 and LD , play a crucial role in the transmission of the allosteric signal. Yet, the role of LD has not been fully elucidated. Therefore, we undertook a study to explain the role of the individual LD residues in inducing and maintaining the proteolytic activity of HtrA. We investigated the influence of amino acid substitutions located within the LD loop on the kinetics of a model substrate cleavage as well as on the dynamics of the oligomeric structure of HtrA. We found that the mutations that were expected to disturb the loop's structure and/or interactions with the remaining regulatory loops severely diminished the proteolytic activity of HtrA. The opposite effect, that is, increased activity, was observed for G174S substitution, which was predicted to strengthen the interactions mediated by LD . Htr AG 174S protein had an equilibrium shifted toward the active enzyme and formed preferentially high‐order oligomeric forms.